It’s January 2013, and a 130,000-tonne asteroid, known as 2012 DA14, is due to pass within 35,000 km of the Earth – that’s closer than one-tenth of the mean distance of the Moon – on 15 February. NASA’s Near Earth Object Program estimates the chance that it will not collide with the Earth as 1 in 556,000. I hope they’ve done their sums right . . .
A hundred-and-thirty thousand tonnes of Solar System scrap
Is heading fast in our direction. But don’t get in a flap:
Astronomers have done the sums and confidently say
It’ll come much closer than the Moon, but everything’s okay.
I hope their observations have been made with high precision,
I hope their theory’s good enough to back up their decision,
I hope they got completely right the flight the asteroid’s taken,
Or else we might not be around to say “You were mistaken”!
[Later note: Phew – they did get it right! But they hadn’t spotted another asteroid, a third of the size of 2012 DA14, that did enter Earth’s atmosphere that very day. It disintegrated over Chelyabinsk, some 1500 km east of Moscow, the shock wave shattering windows and causing many injuries but no deaths.]